Introducing Air-Purifying Pavement Listen Download Embed Share Share this on Facebook (Opens in a new window) Share this on Twitter (Opens in a new window) Share this via Email Russians and tourists wear facemasks to protect themselves from forest fire smog while walking on Red Square in Moscow on August 6, 2010 ( Getty Images ) Produced by Cassie Jones Hosted by Todd Zwillich Produced by PRI and WNYC